Screw pump



FIG. 1 is a front, right, top perspective view of a first embodiment of a screw pump device embodying our design;

FIG. 2 is rear, left, bottom perspective view of the screw pump shown in FIG. 1;

FIG. 3 is a right side view of the screw pump shown in FIG. 1;

FIG. 4 is a left side view of the screw pump shown in FIG. 1;

FIG. 5 is a top view of the screw pump shown in FIG. 1;

FIG. 6 is a bottom view of the screw pump shown in FIG. 1;

FIG. 7 is a front view of the screw pump shown in FIG. 1; and,

FIG. 8 is a rear view of the screw pump shown in FIG. 1. 

The ornamental design for a screw pump, as shown and described. 